Industrial production of textured soy proteins in the form of meatlike products has been underway for several decades. The literature is enormous. Soy protein is known to be plentiful and can be spun, extruded and fabricated into a wide variety of meat replacing products.
The best commercial soy based meat substitutes are expensive and perishable. These are sold either frozen or dry. In their frozen form they must be thawed to use. In their dry form they must be rehydrated to resemble meat. However, drying notably alters and diminishes quality. The poorer soy based meat substitutes are beany to taste, coarse in nature and are sold dry. They are not intended to be used alone.
It would be useful if an inexpensive soy based meat substitute could be manufactured which more closely resembles meat, and which could be maintained in such a condition that it could be used directly. In such a product four conditions would have to be met: (1) the food would have to be less expensive than the meat which it attempts to replace; (2) it should be so similar to meat in texture and moisture content as to permit use in the same manner that meat would be used; (3) it should have appropriate nutritional values; and (4) it should be stable in storage.
Existing art in producing commercial textured soy protein materials now is yielding increasingly palatable products. Bean flavors and tastes are being diminished. Protein content is increasing, now upwards of 70% and more. Price per pound is decreasing. Hence, the first condition above, is being resolved. Such available textured soy products, however, are spongelike in nature. As such, when they are squeezed with the fingers, for example, the liquid they contain when hydrated is readily released. It exudes too quickly to be similar to meat. With meat, such application of pressure results in some release of fluid or juice, but not as a sponge does.
Various mixtures of raw materials are being used to modify extruded soy product texture. Included is the wheat protein gluten. When gluten is added to a dry mix and the mix is then extruded, permanent alterations in the texture of the soy gluten base indeed result. Protein quality is also improved. However in so doing, the gluten is denatured in the extrusion process, and the finished product loses the ability to retain liquids which ability was exhibited originally by the starting materials.
All the presently used textured soy protein manufacturing steps result in an inadequate ability to retain water, water soluble and fat soluble materials. The soy protein is rendered insoluble. All thus result in finished meat substitutes which fail to perform as meat itself does. Because of this poor water retention there is also difficulty in retaining color necessary to create meat appearance, particularly in red meat.